Method of making safety inks



Patented May 3, 1938 PATENT OFFICE METHOD OF MAKING SAFETY INKS Arthur A. Wittncbel, New Rochelle, N. Y., assignor to American Bank Note Company, New York, N. Y., a corporation of New York No Drawing. Application February 14, 1935, Serial No. 6,471

Claims.

The invention relates to method of making safety inks, and more particularly to inks to be used in the production of safety revenue, postage and like stamps and to the method of making 5 such inks.

Revenue, postage and like stamps are attached to various documents, papers, letters and other articles by means of an adhesive, and there is likelihood of users of such stamps removing them 10. from the original article and, with or without the erasure of cancellation marks, to apply them to other articles, thus defrauding the issuing authority of revenue derived from such stamps.

Labels are sometimes affixed to containers of varl5' ious articles of merchandise to indicate the genuineness thereof and to prevent the opening W of the containers for the purpose of adulteration or substitution of the contents of packages but such labels may be removed and re-applied to the same or to a different package containing adulterated or substituted material.

In the practice of such frauds, it is necessary to destroy the adhesive bond between the stamp and the article in order to remove the stamp from an original article. Ordinarily, water soluble adhesives are used and the saturation of the paper of the stamp is requisite to the destruction of the bond to an extent to permit the removal of a stamp preparatory to its re-use upon the same or some other article.

With the above conditions in mind, I have created a method of making a safety ink, an impression made with which will, in all respects, appear to be like an ordinary inked impression 5; and which will be permanent or non-fugitive under all ordinary conditions of use, but which, when subjected to liquid for the purpose of dissolving or otherwise destroying the bond secured by an adhesive, will become so smudged as to clearly indicate that an improper use is being made of the stamp. In this manner the issuing authority or the original user is protected against a fraudulent re-useof the revenue, postage or other stamp having a design impressed thereon with the ink of the invention. Such ink may also be used to incorporate in stamps or similar printed matter, characteristics by which the genuineness of the stamp may be determined by a simple test. I

An ink made by a method embodying the invention includes therein an ordinary vehicle containing any desired water insoluble color pig ment, and in addition thereto, a small percentage of water soluble coloring matter, the proportlon of the latter being so small as to cause the dominant color effect in the impression to be that of the water insoluble pigment. If the water soluble coloring matter be of a different color from that of the water insoluble pigment, there may be a blending of the colors in the ink but the water insoluble pigment will dominate the color. If the pigment and the soluble coloring matter be substantially the same in color, there will be no blending eifect. Whatever color combination may be used, the presence of the water soluble pigment is not apparent in the impression, so that if a fraudulent re-use of the stamps or other articles be attempted, the fraud will be readily detectable.

The vehicle used when mixing the ink will be determined by the printing method with which the ink is used. A safety design printed in intaglio is desirable in the class of work in which the inkis best used, and such oils as are ordinarily used in the vehicles for such inks are employed. The designs with this class of work are ordinarily line designs, although by a proper selection of the vehicle the ink may be adapted for ordinary typographic printing, either line or half-tone, for planographic printing or photogravure printing. The nature of the vehicle used, as stated, will be determined by the printing method to be employed.

In producing an ink embodying the invention for use in steel plate work, Iuse an oil vehicle such as is commonly used in the production of printing inks used in this class of work. The exact character of the vehicle used is subject to wide variation well known to the makers of ink for steel plate printing, so that a detailed description of the vehicle is unnecessary.

Mixed with this oil vehicle is an ordinary color pigment combination. This step in the production of the ink results in an ordinary steel plate printing ink. The coloring matters used are non-fugitive and water insoluble pigments, mixed in the usual way.

With this ordinary printing ink, a small percentage of a batch of an ink containing water soluble coloring matter and a vehicle is mixed. For intaglio printing, the vehicle used is an ordinary heavy oil or varnish vehicle. The soluble coloring matter is an aniline or other coal tar derivative dye which is water soluble.

The mixing of the ordinary ink with its insoluble pigment is carried on separately from the mixing of the vehicle containing the water soluble coloring matter, and the two vehicles with the coloring matter in suspension in each are subsequently mixed together; This practice is followed because the time intervals and other conditions in mixing each type of ink differs from the time intervals and conditions required for the other types. To mix both water insoluble pigment and water soluble coloring matter with the same vehicle at the same time results in an ink product having characteristics which preclude its proper use in printing.

In producing the ink of the invention, I first mix an ordinary printing ink in the usual manner. By ordinary printing ink, I mean an ink containing a Water insoluble pigment and a vehicle consisting of oil, varnish or wax, according to the type of printing in which the ink is to be used. During the mixing of this ink, I add thereto a relatively small quantity of an ink containing a vehicle and Water soluble coloring matter of the character above referred to. If the ink is for use in steel plate printing, this last named ink constituent consists of an aniline dye or other soluble coloring matter derived from coal tar admixed with a varnish vehicle. The water soluble coloring matter may be the same color as the pigment, or a neutral color. Good results can be secured by mixing the soluble coloring matter with substantially an equal amount by weight of the vehicle used in mixing the ink.

The ink containing the water insoluble pigment dominates the color of the ink and may be termed the primary ink in the final mixture. The ink containing the heavier vehicle and the water soluble coloring matter may be called the secondary ink. The time required to mix the secondary ink with the primary ink is much less than that required to mix either the primary or the secondary ink itself.

The secondary ink is admixed with the ingredients of the primary ink toward the final stages of the mixing of this ink, so as to avoid those conditions resulting from over-treatment of the primary ink during mixing. Consequently, if the coloring matter in the two inks is difierent as to color, there will be a blending of the two colors modifying the color or tone of the coloring matter of the primary ink. If the soluble coloring matter be of a substantially neutral color, there will be no such blending.

Good results have been secured with an ink containing about ten percent of the secondary ink and about ninety percent of the primary ink.

With this proportioning of the two inks, the amount of the water soluble coloring matter will be approximately seven percent of the water insoluble pigment. These proportions, however, are subject to considerable variation according to the desired sensitiveness of the finished ink to water or other liquid. The oxidation of the vehicle of the ink in drying protects the water soluble coloring matter to an extent to prevent the smudging of the impression under ordinary atmospheric conditions or when only slightly dampened. The ink is only slightly hygroscopic, and to affect an impression made with the ink, it must be subjected for a material time interval to the action of water or other liquid.

When the ink is used in printing revenue, postage and like stamps, the smudge resulting from the water soluble coloring matter effects the cancellation of the stamp, and prevents its re-use without detection. If the ink be used in the printing of labels, the smudging, in the event of an attempt to remove a label, will indicate that the label has been tampered with and thus place a purchaser of the product upon his guard. In order to determine the genuineness of such a label it is merely necessary to subject the label for a short time to the action of water or other liquid and, in the event of the smudging of the label, the genuineness thereof is indicated.

The ink of the invention is used in making impressions under the same conditions as an ordinary ink used in the same typeof printing, and impressions made therewith do not differ in appearance from those made with ordinary ink.

v If paper bearing an impression made with this ink is subjected to the action of water or other liquid for a very short period, the water soluble coloring matter goes into solution and is absorbed by the paper and spread by capillary attraction to form a smudge corresponding in color with that of the water soluble coloring matter.

If the impression be made from an ordinary engraved or half-tone plate, the lines or dots of the design will remain sharp, so that the original design is clearly discernible because of the permanency of the pigment in the primary ink. This permanency of the original design is a safeguard against counterfeiting. The water soluble coloring matter in the secondary ink merely prevents the removal of the stamp and its re-use without detection.

The essential characteristic of the ink of the invention is the inclusion in the mixture of two dissimilar inks, one of which contains a water insoluble pigment or pigments in a vehicle, and the other of which contains water soluble coloring matter in a vehicle so as to permit the making of an impression, each part of which will contain a permanent ink and a water soluble ink, so that when subjected to water the design of the impression will remain unchanged but the paper upon which the design is impressed will be so badly smudged as to prevent a re-use of the stamp or other article Without detection.

It is not my intention to limit the proportions of the water insoluble pigment and the water soluble coloring matter, or the proportions of the primary and the secondary inks herein specified, it being obvious that such proportions may be varied within a reasonable range without any substantial change in the action of the ink during or following the making of an impression. The proportion of the water soluble coloring matter used is determined largely by the character of the smudge which is desired.

It is desirable to use contrasting colors in the pigment and in the water soluble coloring matter. so as to make the smudging more pronounced. For example, with the pigments commonly used in producing black ink a blue or red water soluble coloring matter has been found to make the smudging pronounced.

Having described the invention, what I claim as new and desire to have protected by Letters Patent, is:-

l. The herein described method of making a safety ink for use in printing safety revenue, postage and like stamps consisting in partially mixing water insoluble pigment and an oil vehicle in one batch, mixing water soluble coloring matter and an oil vehicle in a separate batch, and adding a small percentage of the batch containing the water soluble coloring matter with the batch containing water insoluble pigment while completing the mixing of the batch containing said water insoluble pigment, whereby the water insoluble pigment and the water soluble coloring matter are so intimately associated that an impression made with such ink, as to each part thereof, will contain a permanent ink and a water soluble ink, so that when subjected to water the design of the impression will remain unchanged but a smudge will be formed by the water soluble coloring matter.

2. The herein described method 'of making a safety ink for use in printing safety revenue, postage and like stamps consisting in partially mixing water insoluble pigment and an oil vehicle in one batch, mixing water soluble coloring matter and an oil vehicle in substantially equal quantity by weight in a separate batch, and adding a small percentage of the batch containing the water soluble coloring matter with the batch containing water insoluble pigment while completing the mixing of the batch containing said water insoluble pigment, whereby the water insoluble pigment and the water soluble coloring matter are so intimately associated that an impression made with such ink, as to each part thereof, will contain a permanent ink and a water soluble ink, so that when subjected to water the design of the impression will remain unchanged but a smudge will be formed by the water soluble coloring matter.

3. The herein described method of making a safety ink for use in printing safety revenue, postage and like stamps consisting in partially mixing water insoluble pigment and an oil vehicle as commonly used in the mixing of ink for steel plate printing in one batch, mixing water soluble coloring matter and a heavy oil vehicle in a separate batch, and adding a small percent age of the batch containing the water soluble coloring matter with the batch containing water insoluble pigment while completing the mixing of the batch containing said water insoluble pigment, whereby the water insoluble pigment and the water soluble coloring matter are so intimately associated that an impression made with such ink, as to each part thereof, will contain a permanent ink and a water soluble ink, so that when subjected to water the design of the impression will remain unchanged but a smudge will be formed by the water soluble coloring matter.

4. The herein described method of making a safety ink for use in printing safety revenue,

postage and like stamps consisting in partially mixing water in soluble pigment and an oil vehicle as commonly used in the mixing of ink for steel plate printing in one batch, mixing water soluble coloring matter and a heavy oil vehicle in substantially equal quantity by weight in a separate batch, and adding a small percentage of the batch containing the water soluble coloring matter with the batch containing water insoluble pigment while completing the mixing of the batch containing said water insoluble pigment, whereby the water insoluble pigment and the water soluble coloring matter are so intimately associated that an impression made with such ink, as to each part thereof, will contain a permanent ink and a water soluble ink, so that when subjected to water the design of the impression will remain unchanged but a smudge will be formed by the water soluble coloring matter.

5. The herein described method of making a safety ink for use in printing safety revenue, postage and like stamps consisting in partially mixing water insoluble pigment and an oil vehicle as commonly used in the mixing of ink for steel plate printing in one batch, mixing water soluble coloring matter and a heavy oil vehicle in substantially equal quantity by weight in a separate batch,v and adding substantially ten percent by weight of the batch containing water soluble coloring matter with ninety percent by weight of the batch containing water insoluble pigment while completing the mixing of the batch 7 containing said water insoluble pigment, whereby the amount of water soluble coloring matter in the completed ink will be substantially seven percent by weight of the amount of Water insoluble pigment, whereby the water insoluble pigment and the water soluble coloring matter are so intimately associated that an impression made with such ink, as to each part thereof, will contain a permanent-pink and a water soluble ink, so that when subjected to water the design of the impression will remain unchanged but a smudge will be formed by the water soluble coloring matter.

ARTHUR A. WITINEBEL. 

